An Allied Air Limited Boeing 737-400 freighter on behalf of DHL, registration 5N-OTT performing flight 4W-135 from Libreville (Gabon) to Brazzaville (Congo) with 3 crew, landed on Brazzaville's runway 05. A few seconds after the crew applied reverse thrust the crew heard a bang from the landing gear followed by strong vibrations. The captain took control and brought the aircraft to a stop on the runway.
Congo's BEA released their final report in French only (editorial note: to serve the purpose of global prevention of the repeat of causes leading to an occurrence an additional timely release of all occurrence reports in the only world spanning aviation language English would be necessary, a French only release does not achieve this purpose as set by ICAO annex 13 and just forces many aviators to waste much more time and effort each in trying to understand the circumstances leading to the occurrence. Aviators operating internationally are required to read/speak English besides their local language, investigators need to be able to read/write/speak English to communicate with their counterparts all around the globe).
The report concludes the probable causes of the accident were:
The investigation determined that the most likely sequence of events was a failure of the left main landing gear related to a shimmy that occurred shortly after touchdown, generating dynamic loads that led to the successive failure of mechanical components (shimmy damper, strut, and at a pre-existing intergranular crack).
Contributing Factors
- Excessive wear of the apex joint components (support washer, bushings), causing abnormal play.
- Reduced effectiveness of the shimmy damper due to this excessive play.
- Advanced tire wear, used beyond the recommended replacement limits.
- Presence of a latent structural defect (intergranular crack) not detected during maintenance operations.
Congo's BEA released their final report in French only (editorial note: to serve the purpose of global prevention of the repeat of causes leading to an occurrence an additional timely release of all occurrence reports in the only world spanning aviation language English would be necessary, a French only release does not achieve this purpose as set by ICAO annex 13 and just forces many aviators to waste much more time and effort each in trying to understand the circumstances leading to the occurrence. Aviators operating internationally are required to read/speak English besides their local language, investigators need to be able to read/write/speak English to communicate with their counterparts all around the globe).
The report concludes the probable causes of the accident were:
The investigation determined that the most likely sequence of events was a failure of the left main landing gear related to a shimmy that occurred shortly after touchdown, generating dynamic loads that led to the successive failure of mechanical components (shimmy damper, strut, and at a pre-existing intergranular crack).
Contributing Factors
- Excessive wear of the apex joint components (support washer, bushings), causing abnormal play.
- Reduced effectiveness of the shimmy damper due to this excessive play.
- Advanced tire wear, used beyond the recommended replacement limits.
- Presence of a latent structural defect (intergranular crack) not detected during maintenance operations.
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